When someone is severely wounded (eg. got their leg cut off), how does bloodflow reach the parts of the body which would normally get blood after the parts with torn arteries?
In: Biology
Blood doesn’t circulate through your body one body part at a time. Don’t imagine a big ring road that loops first through your arm, then through your torso, then through your leg, etc. Instead, imagine a big tree-like network with big highways coming from the trunk, which split into smaller roads, which split into streets and finally driveways. And then imagine that each road has traffic going in both directions, separated by a median divider. One direction is an artery, the other is a vein. That’s what your vascular system is like. Blood is being pumped, in parallel, through arteries that carry oxygen-rich blood from the heart to where it is needed, and then back, through veins, that carry the oxygen-depleted blood back to the heart (and then there is a separate loop through the lungs, where arteries carry oxygen-depleted blood away from the heart to the lungs, and veins return the newly oxygenated blood back to the heart to be distributed to the body).
If your leg is cut off, or something similarly severe, it’s like one big branch of the tree being severed. Its a big problem because you can lose a lot of blood that way, but it doesn’t (directly) prevent blood going to places whose branches are still intact (at least, not in the way that you’re imagining – the loss of blood (pressure) can of course lead to a lack of blood going to those places after all).
Arteries branch out from the heart and flow outwards to everywhere at once. It is not like the blood first goes to one leg and then the other. Think like the branches of a tree – if you cut off one branch then the rest of the branches are still connected to the trunk.
That’s not really how the circulatory system works. Mainly blood just flows away from the heart, then back to the heart. Blood does not travel from one limb to the next limb. It’ll go from the heart, to your fingers, back to your heart, and then maybe this Time it goes down the other branch to your toes.
So if your leg is amputated below the knee, the only body parts that blood would go to are already cut off.
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